Dot-in-circle sign in cervical actinomycotic mycetoma: An extremely rare case report

Actinomycosis is an unusual, chronic granulomatous infection caused by Actinomycetes spp. The organism also causes mycetoma, a neglected tropical disease in endemic regions. We present a very uncommon case of extensive actinomycosis of the soft tissues in the neck with perivertebral extension that showed the dot-in-circle sign on magnetic resonance imaging. A 29-year-old male patient presented with progressively enlarging hard posterior neck swelling of 4 years duration. Subsequently, magnetic resonance imaging showed the dot-in-circle sign in an avidly enhancing infiltrative lesion with extensive involvement of the neck and perivertebral soft tissue. The pathologic examination was in line with actinomycosis. The patient responded to high doses of combination parenteral and oral antibiotics.

Madura foot and a continued diagnostic enigma: Dot-in-circle sign on magnetic resonance imaging and ultrasound

Madura foot is a chronic granulomatous disease of the skin and underlying tissues caused by fungi or bacteria. Early diagnosis is important to avoid disfiguring limb deformities. Low clinical suspicion, limited availability of diagnostic tools, and infection with fastidious organisms may lead to misdiagnosis and delayed treatment. Imaging tests can help to make a timely diagnosis in a non-invasive manner. Here we report two patients with a non-classical clinical presentation and a more favorable differential diagnoses who were correctly diagnosed as cases of Madura foot based on the ''dot-in-circle sign'', a specific finding on magnetic resonance imaging and ultrasound.

The "dot-in-circle" sign in musculoskeletal mycetoma on magnetic resonance imaging and ultrasonography

This study aimed to present the ‘dot-in-circle’ sign, which indicates the typical magnetic resonance imaging (MRI) and ultrasonographic (USG) findings for mycetoma involving soft tissue and bone. A total of 8 cases with histopathological proof of mycetoma affecting the musculoskeletal system, and that were examined via MRI and/or coexistent diagnostic ultrasonography between 2004 and 2013 in Songklanagarind Hospital were included in this study. The ‘dot-in-circle’ sign on the MRI and USG images of all the patients was reviewed by two radiologists. The analytic method was descriptive. All cases of musculoskeletal mycetoma revealed the ‘dot-in-circle’ sign on MRI, which was seen as multiple, small, round- to oval-shaped hyperintense lesions separated and surrounded by a low-signal intensity rim (circle), and a tiny, central, low-signal focus (dot). An USG study was available in four patients, and all USG findings demonstrated the ‘dot-in-circle’ sign as a central hyperechoic area (dot) surrounded by hypoechoic tissue (circle). In conclusion, the ‘dot-in-circle’ sign is a typical feature on MRI and USG findings for the diagnosis of musculoskeletal mycetoma.